• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.9 no.3
• /
• pp.1-16
• /
• 2006

The purpose of this study is to develop design model of ecological park as stormwater storage facilities. The results are as follows : First, the design model of ecological park as stormwater storage facilities consider ecological and landscape characteristics such as high efficiency of land use, function as disaster prevention, ecological water purification, formation of habitat for flora and fauna. Second, this study demonstrates two types of plane structure and eight types of designed section. They can be combined and designed depending on conditions of each site. The facilities of stormwater storage conduct disaster prevention system and ecological park. Retention pond in stormwater storage facilities for ecological park also should be made for ecological restoration in the site. Third, the ecological park provide the basis for ecological network from in-site to out-site. Therefore its conservation and restoration plan consider the ecosystems of the site. Fourth, the most important factor for maintenance and management for retention pond is keeping water quality. Sustainable Structured wetland Biotop system is suggested for ecological water purification system in the retention pond which is one of the constructed wetland system using multi-celled aquatic plant and pond. This system can also provide habitat for animals and plants, water friendly park for men, and beautiful landscape.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.40 no.3
• /
• pp.1-8
• /
• 2008

The efficiency of retention systems including compozil-G, hydrocol, compozil-S, and micropolymer under highly closed papermaking system was evaluated using contaminated white waters prepared in the laboratory. Compozil-G and compozil-S performed better in retention than hydrocol and micropolymer systems. This suggested that stronger hydrogen bonding between fiber and guar gum or starch was formed to give stronger flocculation and better retention. Especially compozil-G outperformed compozil-S in retention, and this indicated the presence of stronger interaction between guar and cellulose fibers probably due to their similarity in chemical structure. Two compozil retention systems decreased the cationic demand and COD more effectively than hydrocol and microparticle systems. In particular, compozil-G that uses guar gum was highly effective in decreasing anionic trashes at low dosage.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2008.05a
• /
• pp.495-499
• /
• 2008

This study developed a determination method for a rainwater retention-pumping combination system for roof runoff control. The outflow and stored water volume in the rainwater system was simulated using a water balance equation. Its result is presented in the TPP (Tank capcity-Peak outflow-Pumping rate) curves for rainfall return periods. In a case study on reduction of the peak flow rate of 100-year return period to 5-year in Seoul, The range of pumping rate for $100m^2$ roof area is determined as $0{\sim}25{\ell}$/min. Additionally, retention volume of $8.5{\sim}10m^3$ can be combined with the pumping rate range. That is to say an effective combination of a retention-pumping system capacity can be determined from a system of $8.5m^3$ tank with $25{\ell}$/min to $10m^3$ tank without pump. Using the TPP curves, engineers can determine the effective combination range of retention & pumping system capacity. Furthermore, that can be helpful to decide a detail system capacity for field condition.

• The Journal of Korean Academy of Prosthodontics
• /
• v.45 no.5
• /
• pp.665-674
• /
• 2007

Purpose: The purpose of this study was to investigate the effect of sire and shape of retention element on the bond strength of indirect composite resin and metal. Material and method: The metal disk specimens, each 6mm in diameter, were cast from CrCo alloy. They were divided into 8 groups by applied retention element. retention bead group $B2\;({\phi}\;0.2mm),\;B4\;({\phi}\;0.4mm),\;B6\;({\phi}\;0.6mm),\;B8\;({\phi}\;0.8mm)$, retention crystal group C2 (0.2mm), C5 (0.5mm), C8 (0.8mm) and sandblasting group SB ($110{\mu}m\;Al_2O_3$ blasting) as control. Eighty-eight metal specimens were veneered with $TESCERA^{(R)}$ Indirect resin system. One specimen of each group was sectioned and the resin-metal bonding pattern at the interface was observed under measuring microscope. Other specimens were then tested for tensile bond strength on an Instron universal testing machine at a crosshead speed of 2mm/min. Results: 1. Compared to sandblasting, beads or crystals increased the resin-metal bond strength (P<.05). 2. 0.2mm retention crystals were most effective in improving the resin-metal bond strength (P>.05). 3. 0.2mm beads showed the highest bond strength among retention bead groups, but there was no statistically significant difference (P>.05). 4. Retention crystals tend to be higher in bond strength than retention beads due to wider surface area. 5. The larger retention element, the larger the undercut for the mechanical retention, but the gap at resin-metal interface was also increased. Conclusion: Within the limitations of this study, 0.2mm retention crystals were most effective in improving the resin-metal bond strength.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.2
• /
• pp.434-442
• /
• 2019

Low Impact Development(LID) techniques has been attracting attention as a countermeasure to solve frequent flood damage in urban areas. LID is a techniques for returning to the natural hydrological cycle system by infiltrating the runoff from the impervious surface into the soil. The Bio-retention, one of the LID element technology has outflow reduction effect by reserving and infiltrating storm water runoff from watersheds. Recently, a number of studies have been carried out as interest in the reduction of storm water runoff and non-point pollutants in Bio-retention has increased. However, quantitative analysis on the outflow reduction of Bio-retention applied to small watershed is insufficient. In this study, Bio-retention model was constructed in a small watershed using K-LIDM which is capable of hydrologic analysis. When the storage capacity was increased or dividing the Bio-retention and watershed, the outflow reduction effect was 20% according to the storage capacity increase and 5~15% in the distributed Bio-retention system. The results of this analysis will be used as the basic data of future Bio-retention research related to watershed characteristics, vegetation type and soil condition.

• The Journal of Korean Academy of Prosthodontics
• /
• v.36 no.4
• /
• pp.566-580
• /
• 1998

Implant-supported overdenture is known as a useful appliance, instead of using the conventional complete denture, for better retention and stability. In this study 4 types of materials such as, gold bar/plastic clip(group AuP), gold bar/metal clip(group AuM), palladium bar/plastic clip(group PdP), and palladium bar/metal clip (group PdM) were used to evaluate the retention forces according the type of clips and alloys used for bar fabrication, in the Hader bar system. Repeated insertions and removals of overdenture were conducted in each group. and the retention forces were measured and compared the data of each group according to the number of insertion and removal. The obtained results were as follows, 1. In the comparison of retention forces according to type of bar-clip, retention was increased in the order of group AuM, PdM, PdP AuP. and the retention force of group AuM was significantly increased compared with those of others (p<0.05). 2. In the comparison of retention forces according to the number of insertion, only group PdP showed significant decrease in retention(p<0.05). 3. In the comparison of retention forces according to the type of bar and clip. there was no significant difference in the type of bar, but the retention of plastic clip was significantly higher than that of metal clip when Au bar was used(p<0.05). 4. In the observation of the bar surface, group AuM using Au bar and metal clip showed the most scratches among bar groups.

• The Journal of Advanced Prosthodontics
• /
• v.7 no.4
• /
• pp.323-328
• /
• 2015

PURPOSE. This in-vitro study was designed to evaluate retention forces, microleakage and plastic deformation of a prefabricated 2-implant bar attachment system (SFI-Bar, Cendres+$M{\acute{e}}taux$, Switzerland). MATERIALS AND METHODS. Two SFI implant-adapters were torqued with 35 Ncm into two implant analogues. Before the tube bars were finally sealed, the inner cavity of the tube bar was filled with liquid red dye to evaluate microleakage. As tube bar sealing agents three different materials were used (AGC Cem (AGC, resin based), Cervitec Plus (CP; varnish) and Gapseal (GS; silicone based). Four groups with eight specimens each were tested (GS, GS+AGC, AGC, CP). For cyclic loading, the attachment system was assembled parallel to the female counterparts in a chewing simulator. The mean retention forces of the initial and final ten cycles were statistically evaluated (ANOVA, ${\alpha}{\leq}.05$). RESULTS. All groups showed a significant loss of retention forces. Their means differed between 30-39 N initially and 22-28 N after 50,000 loading cycles. No significant statistical differences could be found between the groups at the beginning (P=.224), at the end (P=.257) or between the loss of retention forces (P=.288). Microleakage occurred initially only in some groups but after 10,000 loading cycles all groups exhibited microleakage. CONCLUSION. Long-term retention forces of the SFI-Bar remained above 20 N which can be considered clinically sufficient. The sealing agents in this study are not suitable to prevent microleakage.

• Journal of the Korean Society for Library and Information Science
• /
• v.49 no.3
• /
• pp.437-456
• /
• 2015

This study aims to compare the retention efficiency of library materials of Automated Storage and Retrieval System(AS/RS) revealed by the literature review to other types of book stacks. Domestic and foreign academic libraries adopted AS/RS as part of a plan to improve the retention efficiency. Literature review reveals that in general, AS/RS is better in the retention efficiency in compare to other types of book stacks. This study compared the amount of library materials stored by the AS/RS of S University Library to the general book stack and the fixed-type and the mobile rack-type of virtual book stacks. The study reveals that AS/RS is up to 6 times more efficient than general book stacks, up to 3.61 times more efficient than fixed-type book stacks and up to 1.45 times more efficient than mobile rack-type book stacks. However, the study claims that the retention efficiency of library materials of AS/RS is lower than what is known.

• Journal of Power System Engineering
• /
• v.20 no.2
• /
• pp.43-50
• /
• 2016

This research proposal is based on a novel non-contact technique of micro-sized bead injection process for fabrication of electronic paper display. This non-contact injection process is based on the principle of electrostatic force and uses micro-sized metal-coated beads dispersed in a solution. The dispersion retention times of three different solutions with viscosities of 10 cps, 100 cps, and 1000 cps were measured by optical equipment showing the retention times of 5 mins, 10 mins, and 30 mins respectively. The dispersion retention rate dropped as the time passed. The dispersion retention characteristic of 1000 cps solution was more stable as compared to those of 10 cps and 100 cps meaning that higher viscosity has better retention properties. The experimental results of bead injection at different viscosity levels of the solution were also measured and a stable injection result was achieved by using 1000 cps solution. This results show that stable injection is dependent on solution viscosity and dispersion.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.40 no.5
• /
• pp.1-10
• /
• 2008

Synthetic mineral microparticles (SMM) is a patented system which has been developed to promote drainage of water and retention of fine particles during papermaking. It is shown in patents that the SMM system can have advantages in both of drainage and retention, compared with montmorillonite (bentonite), which is one of the most popular materials presently used in this kind of application. Turbidity and gravity drainage time were measured using a Britt-Jar test with representative SMM formulations, in order to confirm the efficacy of SMM covering a wide range of compositions and discover effects of some key variables that have the potential to lead to unexpected advantages in terms of the effectiveness of the microparticles, when used in combination with a cationic polyacrylamide treatment of papermaking furnish. An iron silicate showed highest retention performance, as well as suitably fast drainage time relative to other metal silicate and bentonite. Zinc silicate improved retention and drainage. SMM synthesized from aluminum sulfate ($Al_2(SO_4){_3}$) did not show a benefit in retention and drainage, relative to bentonite. SMM synthesized from aluminum chloride ($AlCl_3$) performed better in drainage and retention than bentonite when the Al/Si ratios were 0.76 and 1.00. It was found that when the Al/Si ratio and neutralization are considered, pH variation due to the change of Al/Si ratio can be a key factor to control the size of primary metal silicate particles and the degree of coagulation of the primary particles.